Conventionally, in a motor drive system, a plurality of components, each of which includes a winding set of a motor and a power converter for supplying power to a winding set are redundantly provided, and when one component fails, the motor is continuously driven by other normal component. Particularly, in a device related to main functions of a vehicle, improvement of reliability by redundancy is required for all assumed failures.
Hereinafter, the unit of a group of component for controlling energization to a specific winding set is defined as “system”. Conventionally, a motor control device configured to supply electric power from two systems of power converters to two pairs of winding sets of the motor is often used.
Further, in a field different from the motor control device, a apparatus in which signal transmission units are redundant is known. For example, the transmission apparatus disclosed in Patent Document 1 includes a working unit and a spare unit which commonly have a transmission function of a work data, and a switching control unit for switching a transmission path. When an alarm generates in the working unit, the spare unit functions in place of the working unit.